DVDs become common as optical discs onto which various information such as video information (i.e. main picture information), audio information, sub-picture information, reproduction control information and so on is recorded. According to a DVD standard, the video information (video data), the audio information (audio data) and the sub-picture information (sub-picture data) are packetized each with the reproduction control information (navigation data) and multi-recorded onto a disc in a program stream format of MPEG 2 (Moving Picture Experts Group phase 2), which is a high performance encoding technology. Among them, the video information has data, which is compressed in a MPEG video format (ISO 13818-2), for one stream in one program stream. On the other hand, the audio information is recorded in a plurality of formats (i.e. linear PCM, AC-3, MPEG audio and so on) and has data for up to 8 streams in one program stream. The sub-picture information is defined by a bitmap, and is compressed and recorded in a run length method, and has data for up to 32 streams in one program stream. In the case of the DVD, as described above, a plurality of streams of the selectable audio information (e.g. streams of a stereo sound, a surrounding sound, an original English sound, a dubbed Japanese sound, and the like) and a plurality of streams of the selectable sub-picture information (e.g. streams of Japanese caption, English caption, and the like) are multiplexed and recorded in the program stream format, for one stream of the video information in one movie or film, for example.
On the other hand, a transport stream of MPEG2 standard is coming to be standardized, which is suitable for a data transfer with higher speed and higher volume. According to the transport stream format, a plurality of elementary streams is transferred at the same time, with a far higher transfer rate compared to the program stream format. For example, a plurality of programs, such as a plurality of satellite digital broadcasting channels in one satellite radio wave, is transmitted at the same time in a TDM (Time Division Multiplex) scheme. That is, in the transport stream format, a plurality of videos each having a great amount of data can be multiplexed in the TDM scheme and transferred at the same time. For example, a plurality of movies to be recorded onto a plurality of DVD's or the like can be transferred at the same time.
On the other hand, the audio information in a dual mono format is broadly used in a field of TV broadcasting. The audio information in the dual mono scheme may be information in which Japanese sound as the main audio and English sound as the sub-audio are streamed into one stream, which may be transferred or recorded usually as one signal. Therefore, also as for DVD's, the audio stream in the dual mono format may exist, in addition to the linear PCM or the like, as one of audio streams mentioned above, in the program stream.